This invention relates to devices for protecting electric power transmission systems and the like utilizing computers, and more particularly to a digital protective relaying device provided with a setting device and an indicating device.
A prior known digital protective relaying device utilizing a computer has ordinarily comprised devices for sampling analog electrical values required for the protection at a sampling frequency, and introducing the thus obtained digital values into the computer for controlling the operation of the digital protective relaying device.
In this kind of protective relaying device, however, since there is a fundamental difference in the procedures for handling the analog values and the digital values, the conventional analog value setting device cannot be used for setting digital values.
Furthermore, in the conventional protective relays utilizing analog values, there has been provided no device for assuring the accuracy of the analog values after the values have been once set in the protective relays. The lack of such a confirmation device constitutes a drawback of the conventional device when the device is intended to be used as a protective relaying device of the digital type, particularly when the digital device is used for the protection of an important system such as an electric power transmission system wherein an extremely high precision is required for the protective relaying device.